DIVING FOR SCIENCE........1992 UNIVERSITY OF NORTH CAROLINA AT WILMINGTON UNC SEA GRANT COu.EGE PROGRAM PROCEEDINGS OF THE AMERICAN ACADEMY OF UNDERWATER SCIENCES TWELFfH ANNUAL SCIENTIFIC DIVING SYMPOSIUM September 24-27, 1992 University of North Carolina at Wilmington Wilmington, North Carolina LAWRENCE B. CAHOON EDITOR American Academy of Underwater Sciences 947 Newhall Street, Costa Mesa, California 92627 USA The following pages are reproduced from “Diving for Science………1992: Proceedings of the American Academy of Underwater Sciences Twelfth Annual Scientific Diving Symposium.” Wilmington, NC, September 24-27, 1992. UNDERWATER ARCHAEOLOGY BY BRAILLE: SURVEY ME'IHODOLOGY AND SITE CHARACTERIZATION MODELING IN A BLACKWATER ENVIRONMENT-A STUDY OF A SCUTI'LED CONFEDERATE IRONCLAD, C.S.S. GEORGIA Richard 1. Anuskjewjcz Minerals Management Service Gulf of Mexico OCS Region Office of Leasing and Environment 1201 Elmwood Park Boulevard New Orleans, LOUISIANA 70123-2394 U.S.A. Eroan G. Garrison Marine Archaeology and Maritime History Unit National Oceanic and Atmospheric Administration 1825 Connecticut Avenue, N.W. WASHINGTON, D.C. 20235 U.S.A. Advancement in the science and application of underwater remote-sensing instrumentation has provided the arcluieologist with the tools to conduct research in a blackwater environment. This p•per discusses the development, application, and methodological approach used to conduct an underwater survey and site characterization of a scuttled Confederate ironclad, the c.£.S.. Georiia. in a dynamic tidal and zero-visibility riverine environment. Remote-sensing data collected from this Civil War shipwreck have provided interpretative information to help reconstruct the structural 11nd physiad integrity of this important historic shipwreck as she lies in 18 m of water in SllWnnah Hlirbor, Georgia. Detailed methodological techniques and a zero-visibility •rchaeologictd site characterization model are presented. The model to be presented includes the reconstruction of the site through the use of marine remote-sensing instrumentation tand the integration of these data to formulate the interpretative framework. Introduction Shipwrecks found in United States riverine and coastal environments are generally in waters that have varying degrees of underwater clarity. Many factors interact to reduce water clarity over these wrecks. These factors include turbidity from eediments from surface runoff; biological activity such as algal blooms fed by nutrients entering streams from agriculture, sewage treatment, dredging activities, and their associated dilCharges; and freshet transport of resuspended sediments and organic debris, to name but a few of these 10urces. Suffice to say, the prevailing condition most of the year in major rivers and the coastal littoral is poor-to-zero underwater clarity. Depending upon the particular observer these low visibility conditions are typically termed "blackwater" or "zero visibility." The conduct of archaeological releAl'Ch using standard survey mapping and excavation procedures is difficult if not next to impossible in the most extreme cues of uro visibility. This is particularly so for the wreck site of the C:SS GeorsM· a Confederate ironclad sunk in the Savannah River (Georgia) in December 1864 (ORN Series I, Volume XVI:482). Located 11 miles above the river bar off Fort Jackson (Fig. 1), the site is constantly covered by fresh-to-brackish, silty water rich in organics. Mixed by 6-10 foot tides, the suspended particles are constantly entrained by currents in the water column (U. S. Anny Corps of Engineers, 1982). In addition to poor visibility, water depth, currents, and shipping traffic 1 Diving for Science... 1992 make this a difficult site at which to use divers. These conditions have hampered the use of visual recording techniques and fostered the use of instrumental techniques in the survey mapping and characterization of the CSS Geoq~ia site. These techniques in turn have been embedded in a research methodology and organized to provide data and analysis for several levels of inquiry about the vessel and its context. Figure 1. Location map. Methodology is most correctly defined as the "study of method." It is not the simple explication of a technique or techniques used in the study of an archaeological problem (Pelto, 1970). It is "logic-in­ use" involved in selecting particular observational techniques, assessing their yield of data, and relating these data to theoretical propositions. In the case of the archaeological study of the ~ Geor~a we have attempted to gain, through a wide range of primary observations, data for a series of generalizations about the vessel and its historical period. To make these observations required the use of instrumental techniques and a subsequent enhancement of their data by graphic and digital means. Objectives Our first objective was to characterize the wrecksite of the CSS Geor.aia in as much physical detail as possible (Fig. 2) within the restrictions placed on us by its zero visibility environment. Other objectives were to: a) relate these instrumental data on the wreck to historical data on the dimensions and general form of the vessel when in service during the War Between the States; b) assess the current distribution and orientation of the wreckage; and c) develop alternate models for the visual display and analysis of instrumental data so as to accomplish best the preceding objectives and improve the rigor and specificity of our methodology for zero visibility archaeological research. 2 Anuskiewicz and Garrison: Underwater archaeology --1--... ... ·~-- .... ![-- 11..~~__.._, ~... -.... ~..::.:..~-·.......... ,. t .... ! ' I ' ..................­ ........ •"': ; ; ; _;- : --· .-­ ' - '- ' ·-•·" ........ -~--' 0 0 0 0 0 / Figure 2. Harbor Defense Ironclad (after Porter, 1861) Backpund of the vessel In November 1864, General William T. Sherman began his "infamous" march to the sea from Atlanta to Savannah. Soon after Fort McAllister was captured by Union troops on December 13, the city of Savannah was pressed on two sides by Sherman and on another by a Union naval blockade. At this time, the Savannah Harbor Defense Squadron consisted of eleven armed vessels-seven gunboats and four ironclads. One of these was the CS$ Gem:cia (Fig. 3). During the final hours of the siege of Savannah, the CSS Geo~a was towed to a defensive position across from Fort Jackson to defend the river channel below the city. She trained her batteries against the Union naval advance. Her broadside, facing east, was fitted with two 9-inch Dahlgren smoothbores and two 32-pounder rifles. She also had one 32-pounder mounted in the extremity of the vessel. On her spardeck was a 24-pound howitzer. Fipre 3. Engra"ring of CSS GEORGIA published in Harpen Monthly, 1863. 3 Diving for Science..• 1992 Early on December 20, 1864, Sherman's troops captured Fort Jackson (Baker tt al., 1981), and the Confederates, to avoid its capture, quickly scuttled the CSS Geor1Pa by opening all of the seacocks. Today, she rests in about 55 feet of black, silty water--remarkably preserved, but broken in her superstructure by harbor dredging activities performed since her sinking. She has proven as formidable in her resistance to destruction by these modem foes as she was in the past. Built in 1862, her construction, interestingly, was accomplished through funds raised by members of the Ladies' Gunboat Association. These women of Savannah, Augusta, and other Georgia communities contributed over $115,000 for her construction. The need for such a vessel was intensified during the height of the women's solicitation of funds when, in March 1862, the news reached Savannah of the engagement of the lJS.s Monitor and the CSS Yiqpnia (better known as the USS Merrimac>. This battle proved to be the turning point in the development of naval warfare in Savannah, just as the battle and the war, in general, proved a turning point in the history of naval warfare all over the world. It pointed out that the most effective defense was the ironclad ship, and the most effective offense was the rifled gun. In this atmosphere of excitement and expectation over ironclads, the CSS Geor1:ia was born (Garrison and Anuskiewicz, 1988:74). The CSS Geor~ia was essentially a steam-powered floating battery-a barge-type structure roofed over with wood at an inclined angle and then covered with· railroad iron cladding. Such ironclads were, according to various historical accounts, also described as "floating forts." One observer of the CSS Geowa called it "an ironplated monster a la Merrimac" (ORN Series I, Volume XVI). The CSS Geouia is an enigma because of the discrepancies in her construction details. These discrepancies are directly related to the condition in which she was built during the war. The C.SS Geor~ia remains an enigma and a major source of historical and archaeological data on the 'War between the States." As detailed architectural knowledge does not exist for the CSS Geor~a. her reconstruction necessarily proceeds on thin ground. The vessel had no keel, was unstable in the water, was too heavy and cumbersome to float without the aid of her engines or to maneuver under her own power (Kollack, 1950), first planned as an ironclad "gunboat," but she was actually used as a floating battery. These criteria present a number of possibilities for consideration in a realistic reconstruction. The CSS Geo[lia floated for 20 months on the Savannah River, moored near Elba Island where, if the situation required, she could bring her broadside to bear on either channel of the river (Nordoff, 1863). In December 1864, when General Sherman was approaching the city of Savannah on his famous march, the CSS Geor~a's fate was decided: as per orders from Commander Hunter, because of her lack of sufficient motive power, she was to be scuttled if Union forces reached Savannah (ORN Series I, Volume XVI:482). On December 20, 1864, the city of Savannah was evacuated and the CSS Geowa was scuttled, making her resting spot for the next century and more on the bed of the Savannah River.